1. Field of the Invention
The present invention relates generally to automotive engines and tools for the repair and replacement of engines and engine parts. The present invention relates more specifically to a tool that facilitates the removal and replacement of valve springs on an internal combustion engine as may be required for the replacement of valve seals on the engine.
2. Description of the Related Art
Many components on internal combustion engines for automobiles wear out over time and must be replaced. Among these components are the valve seals positioned on the engine cylinder heads. The typical cylinder valve component comprises an elongated shaft or stem with a valve head that rests in a valve seat or seal thereby closing an intake or exhaust port from the cylinder. The typical valve structure includes a strong spring that maintains the valve head tightly against the seat or seal unless a rotating cam forces the shaft downward and thus the valve head away from the seal. The valve spring is typically connected to the valve stem in a removable fashion at one end of the shaft.
In order to replace the valve seat or valve seal which wears out over time, it is necessary to compress the valve spring away from its point of attachment to the valve stem. In this manner the attachment mechanism (typically a split ring or collar) can be removed and the spring released. One of the most difficult and dangerous activities in the repair and replacement process for automotive mechanics is the compression of these strong valve springs in order to carry out their removal and the replacement of the valve seals. It is not uncommon for the manual compression of the spring to accidentally release and injure the mechanic in the process. It is well known to use lever based mechanisms for compressing the spring with one hand while attempting to remove the split ring or collar from the valve shaft with the other hand. If the lever slips, the spring and/or the split ring components might easily be directed with some force at the mechanic carrying out the operation.
There are instances in the repair of automotive engines where the removal of valve springs can be carried out with the cylinder head in place on the engine block. There are other circumstances where it is preferable to conduct repairs on the cylinder head on a work bench separate from the engine block.
Various efforts have been made in the past to provide tools to facilitate the removal of valve springs from the cylinder heads of automotive engines. Some of these efforts in the past attempt to provide tools for removal of the valve springs while the cylinder heads are in place on the engine while others rely on first removing the cylinder heads from the engine and carrying out their disassembly on a work bench or the like. Examples of each of these approaches can be found in the following patent disclosures.
U.S. Pat. No. 3,977,064 issued to Mote et al. on Aug. 31, 1976 entitled SITU VALVE SPRING COMPRESSION TOOL describes a valve spring compressor tool intended specifically for use in conjunction with cylinder heads that incorporate heavy duty double valve springs. The tool includes a support bridge that is bolted to the rocker housing across the valves to be compressed. A shaft is threaded into the cross arm and is aligned so that rotation causes it to exert a compressive force down on the springs and retains them in a compressed position for work on the valve assembly.
U.S. Pat. No. 3,979,811 issued to Kammeraad on Sep. 14, 1976 entitled OVERHEAD CAMSHAFT AND VALVE TRAIN INSERTION AND REMOVAL TOOLS describes a tool intended for use in conjunction with overhead camshaft assemblies. The tool includes a longitudinal base for attachment to the cylinder head which positions a number of rocker members that project under the camshaft to a position over the valve springs. Each rocker member retains a threaded screw that when turned pivots the rocker so as to compress the valve spring. This permits the removal of the camshaft or other work to be carried out on the valve assembly.
U.S. Pat. No. 3,984,909 issued to Velazquez on Oct. 12, 1976 entitled VALVE STEM SEAL CHANGING TOOL is directed specifically to a tool that facilitates the removal and replacement of valve stem seals. The best view of the overall tool can be seen in FIG. 4 of the patent wherein a threaded rod with a turning handle may be positioned immediately over the valve spring for compression. A sliding guide rod is positioned on the cylinder head to facilitate the individual placement of the spring compressor over the valve to be worked on. The tool contemplates work on only a single valve at a time and the sliding of the tool across the cylinder head as work progresses. An additional tool component may be inserted through a spark plug hole in the cylinder head to help retain the valve in position after the valve spring has been released.
U.S. Pat. No. 4,022,453 issued to Durgan on May 10, 1977 entitled CLAMP FOR ENGINE HEAD SERVICE TEST BENCH describes a service bench that includes a clamp designed to facilitate the compression of valve springs on an internal combustion engine cylinder head. Other functions of the clamp are anticipated, but it is primarily designed to be positioned across a pair of valves with a bridge. A threaded rod pushes on the bridge between the valves in a manner that compresses the springs for the two valves and facilitates their removal.
U.S. Pat. No. 4,780,941 issued to Tucker on Nov. 1, 1988 entitled QUICK MOUNT HAND VALVE SPRING COMPRESSOR describes yet another valve spring compression tool intended to operate in conjunction with a single valve spring at a time. The tool includes a device that is attached to a threaded rocker stud on the cylinder head and positions a metal yoke over the individual valve spring. It appears that the unique feature of this device is the manner in which it may be removably attached to the threaded stud on the cylinder head and hand cranked so as to compress the valve spring.
U.S. Pat. No. 5,042,128 issued to Barbour on Aug. 27, 1991 entitled TOOL FOR REMOVING VALVE SPRING RETAINER OF A VALVE'S ASSEMBLY describes yet another rocker plate type tool that is positioned in place of the valve rocker over the valve spring assembly. A threaded rod is positioned on a non-threaded seat within a push rod bore of the engine cylinder head. This seat causes the threaded rod to push up on the rocker plate when turned so as to compress the valve spring on the opposite end of the rocker plate. The patent appears to only address the placement of the tool in conjunction with a single valve spring at a time.
U.S. Pat. No. 5,241,734 issued to Brackett on Sep. 7, 1993 entitled APPARATUS AND METHOD FOR REMOVING AND INSTALLING VALVE-SPRING RETAINER ASSEMBLIES describes a tool that employs an existing spark plug opening for the purpose of mounting to the engine cylinder head. Like many of the previous patents, it relies on a single lever positioned on the cylinder head in a manner such that the forced movement of one end of the lever causes the compression of the valve spring on the opposite end of the lever. An alternative embodiment in this patent is shown in FIG. 4 wherein a gang of four valve springs may be compressed through the use of an x-shaped compression tool secured to the cylinder head at the center of the tool. A similar assembly is contemplated for two side-by-side positioned valve springs as shown in FIG. 5.
U.S. Pat. No. 5,339,515 issued to Brackett et al. on Aug. 23, 1994 is a continuation-in-part of the earlier Brackett patent and “improves” upon the device by providing a handle for depressing the lever described above. As shown in FIGS. 6 and 7 the lever handle is intended to speed up the process of compressing the spring versus a threaded compression screw. It would appear that there are some safety concerns with the hand operated mechanism described in this patent. In addition, there is no indication that multiple valve springs are worked on at the same time.
U.S. Pat. No. 5,371,932 issued to Bryan et al. on Dec. 13, 1994 entitled MULTIPLE VALVE SPRING COMPRESSOR describes a bench device consisting of a rectangular base of sufficient size to support an entire cylinder head assembly. Incorporated into the tool is a longitudinal plate best seen in FIG. 2 having a long open slit in its center. The open slit is sized and positioned to fit over the valve stems, while the balance of the plate is positioned to compress the valve springs. Operation of the tool is by means of an expandable device such as a hydraulic cylinder that presses down on the plate. Various orientations of the cylinder head are provided for in the assembly.
U.S. Pat. No. 5,689,870 issued to Robey on Nov. 25, 1997 entitled VALVE SPRING COMPRESSION TOOL describes a fairly simple device intended to be used in conjunction with a standard ratchet wrench. The tool includes a rocker plate that is positioned in place of the valve rocker and is forced downward by the progressive threading of a special socket onto the rocker arm stud. Here again, there is no indication that more than a single valve can be worked on at a time.
U.S. Pat. No. 5,950,293 issued to Hamilton et al on Sep. 14, 1999 also describes a bench tool device for working on an engine cylinder head once it has been removed from the engine. A pneumatically operated valve spring clamp may be moved from side-to-side across the cylinder head so that its compression shaft may be appropriately positioned above each valve spring. Here again a specialized clamp or bracket for holding the cylinder head permits a rotation around a longitudinal axis of the cylinder head in order to appropriately position the valve springs for compression.
Each of the above efforts in the past to provide tools to facilitate the removal of valve springs suffer from either excessive complexity or difficulty of use. It would be desirable to have a simple tool mechanism that would facilitate the removal and replacement of valve springs on a cylinder head both in place on an engine within a vehicle or separated from the engine on a work bench. It would be desirable for such a tool to be simple, inexpensive, easy to apply and safe in its operation.